I. Field
The present invention generally relates to communications, and more particularly, to switching of serving access points in wireless communication systems.
II. Background
In telecommunications, especially wireless communications, communication environments are not static but rather dynamic. In a mobile communication setting, some mobile communication entities, commonly called the mobile stations, may move to different locations under different communication conditions at different times.
In a wireless network, the mobile station accesses the main network via certain infrastructure communication entities, commonly called the base stations.
The communication connection in which data flow from the base station to the mobile station is called the forward link (FL). Likewise, the communication connection in which data flow from the mobile station to the base station is called the reverse link (RL). Communication conditions are not always the same for both the FL and the RL. For example, a mobile station may be communicating with a serving base station which has a highly congestive RL traffic but a relatively open FL flow. For the mobile station to stay with the base station for both FL and the RL while a better RL is available from other base stations may not be the best use of communication resources.
In addition, for a mobile station to change from one base station to another to access the main network, be it for a FL change or a RL change, it is preferable that the data packets exchanged during and after the change remain intact. This is especially true for time-sensitive data packets, such as data packets exchanged in a Voice over IP (VoIP) call. Unlike elastic or best-effort data packets, erroneous or missed time-sensitive packets during transmissions are not always resent. Thus, disruptions of time-sensitive data packets during change of base stations can affect quality of services.
Accordingly, there is a need for the mobile station to freely select any serving communication entities for the assignment of the FL and the RL, so as to adaptively and efficiently utilize available communication resources, yet maintaining data integrity during the handoff process.